*{
    padding: 0;
    margin: 0;
    list-style: none;
    box-sizing: border-box;
}
html,body{
    width: 100%;
    height: 100%;
    background-color: black;
}
.box{
    width: 340px;
    min-height: 300px;
    border: 1px solid #ccc;
    margin: 30px auto 0;
}
.users{
    display: flex;
    flex-wrap: wrap;
}
.users li{
    width: 80px;
    height: 40px;
    margin: 15px;
    background-color: red;
    color: white;
    line-height: 40px;
    text-align: center;
}
.box button{
    display: block;
    margin: 20px auto;
    height: 40px;
    width: 80px;
    background-color: purple;
    color: white;
    border: none;
}